Results of surgical treatment of patients with rectal cancer with submucosal invasion and factors of negative prognosis

Challenges in determining the optimal extent of surgical treatment for patients with rectal cancer with submucosal invasion is still an actual problem in oncoproctology.

AIM: to evaluate the oncological efficacy of “salvage” secondary total mesorectal excision (sTME) in patients with T1 rectal cancer combined with risk factors for metastasis to regional lymph nodes.

PATIENTS AND METHODS: the study included 126 patients with T1 rectal cancer combined with risk factors for regional metastasis, who were treated at the A.N. Ryzhikh National Medical Research Center of Coloproctology from January 1, 2015, to December 31, 2025. Primary total mesorectal excision (pTME) was performed in 40/126 (31.7%) patients due to suspected involvement of regional lymph nodes or depth of invasion of T2 or greater. Transanal endoscopic microsurgery (TEM) for local tumor excision was performed in 86/126 (68.3%) patients. After identification of risk factors for metastasis upon comprehensive pathological examination, all patients were offered salvage surgery — secondary total mesorectal excision (sTME) — which was performed in 22/86 (25.6%) patients, while 64/86 (74.4%) refused radical surgery.

RESULTS: there were no mortalities in any group. The rate of postoperative complications did not differ significantly between the sTME group 6/22 (27.3%) and the pTME group 10/40 (25%) (p = 1). However, complications after TEM occurred 6 times less frequently 4/86 (4.7%) compared to resections (pTME + sTME) 16/62 (25.8%) (p = 0.0003). Patients in the sTME and pTME groups demonstrated a high rate of locoregional metastasis: 22.7% (5/22) after sTME and 32.5% (13/40) after pTME, respectively. The quality of the surgical specimen after sTME was significantly worse than after pTME: 13/22 (59.1%) vs. 10/40 (25%), p = 0.01. The two-year disease-free survival (DFS) was 86.2% (95% CI: 77.2–100) in the pTME group, 100% (95% CI: 100–100) in the sTME group, and 71.6% (95% CI: 67.7–92.6) in the TEM group. Applying the Bonferroni correction, where differences were considered significant at p < 0.017, a certain trend toward worse outcomes was observed in the TEM group compared to the sTME group (p = 0.03). The probability of recurrence in the TEM group without subsequent resection increased by 4.1 times (HR = 4.1; 95% CI: 1.1–15.2; p = 0.03). A similar trend was found in the rate of locoregional recurrences between the sTME and TEM groups (p = 0.05). The probability of local recurrence was 4.8% (95% CI: 0–13.4) in the pTME group, 0% (95% CI: 0–0) in the sTME group, and 23.9% (95% CI: 4.0–25.0) in the TEM group. Thus, the probability of local recurrence in the TEM group was 4.1 times higher (HR = 4.1; 95% CI: 1.0–17.3; p = 0.05) compared to the sTME group.

CONCLUSION: the treatment strategy for patients with rectal cancer invading the submucosal layer and presenting negative prognostic factors represents a complex challenge. The necessity of sTME is dictated by the lack of difference in postoperative complication rates compared to pTME, as well as the high frequency of metastases to locoregional lymph nodes. Refusal of sTME after identifying high-risk factors for metastatic involvement of regional lymph nodes is associated with a significant decrease in disease-free survival rates.

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